Save relations on Link creation instead of parent save

[emteknetnz]

Currently the has_one relations between Link and parent for both the single and the multi link field are updated when the parent is saved e.g. the page edit form is saved

This can result in a fairly uninuitive situation where orphaned links can be created if the use navigates away from the page without saving. This will get particularly confusing once link sorting has been implemented

Excluded

• Updating the parent save/published button state - this will be done in another card

Acceptance criteria

• Link relations are saved to the database on Link creation (modal save) rather than parent save

PRs

• ENH Save relations on link creation #146

[GuySartorelli]

Merged PR